Watch testing apparatus



May 18, 1965 L. E. ELLlsoN WATCH TESTING APPARATUS I 3 Sheets-Sheet lFiled March 25, 1962 May 18, 1965 L. E. r-:LLlsoN 3,183,706

WATCH TESTING APPARATUS 3 Sheets-Sheet 2 INVENTOR. .@Za/I/ May 18, 19651 E. ELLlsoN WATCH TESTING APPARATUS 3 Sheets-Sheet 3 Filed March 23,1962 illm--- NNI QW NNN n lmm wml United States Patent Oiice 3,183,706Patented May 18, 1965 3,183,796 WATCH TESTING APPARATUS Lynn E. Ellison,476 Golf Road, Crystal Lake, Ill. Filed Mar. 23, 1962, Ser. No. 181,8854 Claims. (Cl. 7S- 6) This invention relates to apparatus for comparingthe beat or oscillation frequency of a watch movement with a referencefrequency.

Watch testing apparatuses of the type which compares the oscillationfrequency of a watch movement with a predetermined reference frequencymay take numerous forms. One form of such apparatus indicates the on andorf frequency conditions of the watch movement under test by thedeflection of the pointer on the current indicating scale of a directcurrent (DC.) meter movement. When the oscillation frequency of thewatch movement corresponds to the reference frequency, the deflection ofthe pointer on the face of the meter is constant, and when suchrelationship is not present, the deection of the pointer continuouslyand progressively varies over substantially the entire extent of thescale.

U.S. Patent No. 2,541,286 discloses a watch testing apparatus of thetype just described for testing and adjusting the watch balance beforeit is inserted into a watch movement. A circuit is therein disclosed forcontrolling the flow of current through the meter movement which circuitutilizes a pair of series connected switches which are respectivelymechanically opened and closed by the watch balance and a standardbalance in accordance with the oscillation frequencies thereof. There,each of the Switches comprises the blade of the hair spring engaging anddisengaging a pair of electrically insulated pins which are identical tothe curb pins in a watch movement. The standard balance oscillates atthe same frequency as the desired oscillation frequency of the watchbalance under test. When both switches are simultaneously closed, a DC.voltage source is connected to the meter movement. When the oscillationfrequency of the standard balance corresponds to the oscillationfrequency of the watch balance under test, the relative phase of theinstants of opening and closing of the series connected switches willremain constant, and current pulses of constant duration pass throughthe meter movement. The resulting constant deflection of the meterpointer indicates that the watch balance under test is on frequency.However, if that relationship does not exist between the oscillationfrequencies of the standard balance and the watch balance under test,the relative phase of the instants of the opening and closing of theseries connected switches will progressively vary. The resultingprogressively varying deflection of the meter pointer indicates that thewatch balance under test is olf frequency. The hair Spring of the watchbalance is adjusted to the proper length to cause the oscillationfrequency of the watch balance to correspond to that of the standardbalance, the hair spring is marked `and severed at that length, and thenthe adjusted watch balance is inserted in the Watch movement. Y j

It is an object of the present invention to provide improved testapparatus which indicates the on and off frequency conditions of thebalance of a watch movement in the general manner above described,and-wherein no physical or direct electrical connections are requiredbetween the test apparatus and the watch movement under test or itsbalance. To this end, the present invention utilizes a microphone whichresponds to the audible ticking of the watch or its movement, enablingthe test apparatus to be easily and conveniently used by even nonskilledpersons. A related object of the invention is to provide a watch testingapparatus as just described which does not require a standard watchmovement or balance.

To this end, the present invention utilizes the commercial alternatingcurrent (A.C.) power line voltage as the source of the referencefrequency, such voltage being generally kept by the power companiesprecisely on frequency, so that the user of the test apparatus need notbe concerned about the accuracy of a standard watch movementincorporated in the test apparatus as heretofore used.

The electrical signal generated by a microphone responding to the beatof a watch movement will comprise a series of spaced signal unitsrepresenting the various beats of the watch. Each of these signal unitscomprises contiguous pulsations representing the vibration of one beatof the watch movement. In the most advantageous form of the invention,electrical signals derived from the output of the microphone areutilized to control the conductive state of an electronic switchcontrolling the coupling of a current source to the meter movementreferred to above. The control of the electronic switch is preferablyeffected through a bistable circuit which is triggered into one state ofoperation at the beginning of each signal unit of the microphone output.The electronic switch is rendered conductive during this state of thebistable circuit. The bistable circuit is triggered into its oppositestate to render the electronic switch non-conductive upon the occurrenceof a reference timing pulse derived from the A.C. power line voltagepreviously referred to.

The proper operation of a timing circuit of the type described abovedepends in part upon the nature of the signals utilized to trigger thebistable circuit and the relative frequencies or phases of the referencefrequency and the narrow range of watch oscillation frequencies eX-pected with the watch movements to be tested. Difficulties can occur,for example, if the duration of the beats of the watch movement overlaptwo cycles of the reference frequency. Also, the multiple pulses makingup each signal unit at the output of the microphone can in someinstances cause false multiple triggering of a bistable control circuitto which the signals are fed.

It is, therefore, another object of the invention to so design the testapparatus that the diiliculties referred to above are not present.

To this end, in accordance with another aspect of the present invention,the reference frequency derived from the A.C. power line voltage isobtained by means including a pulse forming circuit which producesrelatively narrow pulses from the rather wide sinusoidal power linevoltage waveform. These narrow pulses are fed through a pulse dividercircuit to reduce the frequency of the pulses to a frequency which ismost advantageously 3, 4 or 5 times that of the desired beat frequencyof the watch movements to be tested, which are generally tive beats persecond. As above indicated, in the most advantageous ferm of theinvention the reference pulses are utilized to trigger a bistablecircuit to a state which renders the electronic switch feeding the metermovement to its nonconductive condition.

In accordance with another aspect of the invention, the output of themicrophone which picks up the beats of the watch movement are fed to apulse shaping circuit which effectively generates a single narrow pulsecoinciding with the start of each heat indicating signal unit at theoutput of the microphone. The subsequent pulsations of each signal unitare eliminated from the input to the bistable circuit. The pulse shapingcircuit most advantageously is a monostable multivibrator which providesa square pulse having a duration greater than the longest duration of abeat pulsation expected from the watch movements to be tested. Thesquare wave output of the monostable multivibrator is fed through adifferentiating and rectifyleading edge of the square wave output of themonostable multivibrator.

These and other objects, features and advantages of the invention willbe apparent upon making reference to the specification to follow, theclaims and the drawings wherein:

FIG. l is a simplified box diagram of an electrical circuit illustratingthe watch testing equipment of the present invention;

FIGS. 2a through 2]' are timing diagrams of some of the current andvoltage waveforms in the circuit of FIG 1 for different conditions ofthe watch under test; and

FIG. 3 isa detailed circuit diagram of the circuit shownV in box form inFIG. 1.

Referring now to FIG. l, the watch under test, winch in place orotherwise held adjacent to a conventional microphone 4 which generateselectrical signals corresponding to the vibrations of each beat or tickof the watch movement 2. The electrical output of the microphonerepresenting the vibrations lof a single beat of the watch is indicatedby waveform S1 in FIG. 1. This waveform comprises contiguous alternatingpulsations which cease at the end of each beat or tick of the watch.This beat indicating waveform reoccurs at the beat frequency of aboutfive beats per second in most watches.

The electrical output of the microphone fi is 4fed to amplifier 6 whichproduces an amplified signal corresponding to the waveform Si but ofmuch greater magnitude. The amplifier output is fed through a rectifier8 lwhicl'rprovides pulsations of -only a single polarity'. The output ofthe rectifier 8 is fed to one of the control inputs `of Ia monostable orone shot multivibrator l@ which is thereby triggered from astaole resetor reference state t-o an unstable state by the first of the pulsationsof each beat indicatinfy signal received from the amplifier d. Themultivibrator 10 remains in its unstable state fora fixed predeterminedperiod, depending upon the time constant of the circuit involved, suchtime period being purposefully designed to be greater than the longestduration beat indicating signal expected from the watch movements to betested. The monostable multivibrator then returns to and stays in itsreset or referenceVV state until it receives the next beat indicatingsignal from the amplifier 6. The output of the monostable multivibratorcircuit 1t) has a square waveform 21 as shown in FIG. 1 with relativelysteep leading and trailing edges. Y

The output of the monostable multivibrator 10 is connected to adifferentiating network 12 which comprises a capacitor 14 in series witha resistor. 16. As is conventional in differentiating networks,the'timeV constant Vthere-V of is made sufficiently short that thevoltage appearing across the resistor 16 when a square wave is fed tothe input of the network comprises voltage spikes or pulses P1 and P2 ofopposite polarity coinciding respectively4 with the leading and trailingedges of the square Wave 21. The negative pulseV P1 coincidingwith theleading edge of each square wave is fed to the input 19 ofa bistable orip-opcircuit 20V where it triggers the same from a reset state ofoperation to Yan opposite state of i 60 Vl5 is generally indicated byreference numeral 2, is clamped alternating current (A.C.) power system32 which in the United States generally has a frequency of sixty cyclesper second. The power system 32 also may be fed to the input of asuitable D C. power supply source 34 Which supplies D.C. energizingpotential to the bistable control circuit 2t) as well as other parts 4ofthe circuit.

The pulse forming circuit 3G generates one narrow pulsation P3 of agiven polarity for each cycle of the A.C. voltage fed to the input ofthe pulse forming circuit 30. The output of the pulse forming circuit 30is connected to a frequency divider 36 which provides a square waveoutput S2 at a frequency which bears an integral numerical relation tothe desired watch beat frequency (tive beats per second) and which ismore comparable to the watch beat frequency than sixty pulses (orcycles) per second. Thus, the frequency divider 36 may produce awaveform at a frequency of fifteen cycles per second. This waveform isfed to a differentiating network 38 comprising a capacitor 46 and aresistor 42. The pulses Vdeveloped across resistor 42 are fed to theinput 44 of the bistable circuit 2@ to reset the same.

The manner in which the circuit shown in FIG. 1 operates to indicate theon and ofi frequency conditions of the watch under test is bestunderstood by an explanation of various waveforms in the circuitasrshown in FiGS. 2(a) through 2(1') The various waveforms shown inFIGS. 2(rz) through 2(1') are drawn on a common time scale .andillustrate the operation of the circuit shown in FIG. 1 for threedifferent conditions of the watch 2. FfG. Z(a) illustrates the referencefrequency pulses (fifteen pulses per second) fed to the input iiofbistable circuit 20. FIGS. 2(b) through 2(d) illustrate variouswaveforms controlled by thebeat of the watch where the latter is onfrequency, namely a frequency of tive beats per second. FIGS. 2(e)through 2(g) are waveforms corresponding to FIGS. 2(1)) through 2(d )foran on frequency condition where the p phase of the watch beats isdifferent from FIG. 2(b),

to the multivibrator Vcircuit 20 or the multivibrator cirto a D.C. meter23.V The' electronic switch 24 Vremains in a conductive state until thebistable circuit Zts reset.b A circuit fory supplying referencefrequency pulses forV resetting the bistable circuit Ztl is providedincluding` a pulseY forming circuit 30 whoseA input is connected to anY1 Direct current (D.C.) i' from the source of direct current voltage26'Vis'then fed' prises a number of contiguous vibrations or pulsations.

FIG. 2(0) shows the pulses fed to the input 19 of the bistable circuit2b coincident with the beginning of the beat indicating signals of FIG.2(b). FIG. 2(d) shows the periods of conduction of the electronic switch24, which are initiated by the beat indicating pulses of FIG. 2(0) andterminated by the next occurring reference pulses of FIG; 2(zz). Sincethe reference pulse frequency of fifteen pulses per second bears anintegral numerical relation- .ship with respect to the beat frequency ofthe watch 2, the

relative phasebetween the beat indicating pulses of FIG.

l 2(0) and the reference pulses of FIG. 2(a) will remain constant; sothat the conduction intervals of the electronic switch 24 willremainconstant. The pointer'ZS of the meter 28 will thenY have a substantiallyconstant deflection... Themeter movement is fairly heavily damped sothat therpeinter 28 will remain fairly stationary with only a smallnoticeable oscillation.v

FIGV.'2(e) illustrates'the amplified watch beat indieating signalsoccurring at tive signals per second where Ithe watch beats have a laterphaserelationship with respeot tothe reference frequency pulses shown inFIG. 2(lz) and Vthus the conduction intervals of the electronic switch24 are decreased accordingly. The deliection of the pointer 28 of themeter 28 will be less than that presentvunder the condition of FIGS.2(b) through 2(d), but

the deliectionY will remain substantially constant, indicating .the onfrequency condition of the watch 2.

phase between the'beat indicating signals and the reference frequencypulses of FIG. 2(a) will vary with time. Accordingly, .the duration ofthe conduction intervals of the electronic switch 24 for successivewatch beat pulsations will vary as indicated, so that the deliection ofthe pointer 28 will vary progressively with time.

Refer now to the circuit diagram of FIG. 3 which illustrates a preferredcircuit for the form of the invention shown in box form in FIG. l.Corresponding elements in FIGS. 1 and 3 have been indicated by similarreference numerals. As shown in FIG. 3, the microphone 4 is connected toa plug 50 which is insertable into a conventional jack 51. When insertedin the jack, the microphone 4 is connected between a ground line 53 andthe input side of a capacitor 54 connected to the first stage of a threestage amplifier 6. The amplifier 6 is preferably a conventional typetransistorized ampliiier including three PNP transistors 56, 58 and 60.The transistor 58 -has associated therewith a potentiometer 61 having amovable wiper 61' which varies the amplitude of the output obtained fromthe ampliiier stage involved.

The various transistors are energized through a common line 62 connectedthrough a voltage dropping resistor 64 and a line 66 to the negativeterminal 68 of the direct current power supply 34. The output of thethird stage of the amplifier 6 is taken at an output terminal 70 towhich is connected a branch circuit including a capacitor 72 and anormally-open jack 74 into which ear phones or a speaker may be pluggedso that the ticking of the watch can be heard if desired.

Another output branch circuit extends from the output terminal 70through a capacitor 75 to the anode of a rectilier 7 S whose cathode isconnected to the ground line 53. The rectifier 78 acts as a clampingdevice which clamps the varying output of the rectifier to ground,thereby giving a voltage doubling effect. The resulting negative goingvoltage is fed through the previously described rectifier 8 to the inputof the monostable multivibrator 10.

The monostable multivibrator 10 may be a conventional transistor oneshot multivibrator including two transistors 82 and 84 of the PNP type.The collector electrode 82a of the transistor 82 is connected through aresistor S5 to the negative line 66. The base electrode 82b of thetransistor 82 is connected to the output side of the rectifier 8. Aresistor 86 is connected between the base electrode 8217 and the groundline 53. A resistor 88 is connected between the emitter electrode 82C ofthe transistor S2 and the ground line 53. A capacitor 90 is connectedbetween the collector electrode 82a of the transistor 82 and the baseelectrode 84]; of the transistor 84.

The collector electrode 84a of the transistor 84 is connected through aresistor 91 to the negative line 66. The emitter electrode 84C of thetransistor 84 is connected to the ungrounded side of the resistor 88.The transistor 84 is initially biased into a highly conducted stablestate by the connection of the base electrode 84b of transistor 84through a resistor 93 to the negative line 66. The resulting negativevoltage on the base electrode 84h will render the transistor 84 normallyhighly conductive. The resulting voltage developed across the resistor88 used in common with the emitter circuit of the transistors S2 and 84will bias the transistor 82 to a non-conductive condition.

The first negative pulse of a beat indicating vibration appearing at thebase electrode 82h of the transistor 82 will initiate conduction of thetransistor 82. This will result in a sudden change of the voltage at thecollector electrode ,82a `from a highly negative value to near ground orzero voltage, anda relatively positive vol-tage is `coupled through thecapacitor 90 to the base electrode 841; of the transistor S4 to renderthe same relatively non-conductive. This will cause the voltage on thecollector electrode 84a thereof to become more negative. 'The resultingnegative voltage is rcoupled through a feedback line 97 and a resistor99 to the base electrode 82b of the transistor 82. The feedback circuitrapidly causes the transistor 82 to become highly conductive and thetransistor 84 to become non-conductive. This condition remains until thecapacitor substantially Ifully charged to the new voltage conditions ofthe circuit, whereupon the connection of the base electrode 84b throughthe resistor 93 to the negative line 66 once more becomes effective torender the transistor 84 non-conductive.

The voltage waveform on the feedback line 97 constitutes the output ofthe multivibrator and comprises a single square wave for each beatindicating signal fed to the input of the monostable multivibratorcircuit 10.

As previously indicated, the period during which the monostablemultivibrator circuit 10 is in its unstable state is longer than thelongest expected duration of each watch beat vibration, so thatIsubsequent pul-ses of each beat indicating signal will have no eifecton the multivibrator circuit 10.

The square wave output of the multivibrator circuit 10 is fed to adifferentiating network including capacitor 14 and resistor 16. A sharpnegative and a sharp positive pulsation will appear across the resistor16 coinciding respectively with the leading and trailing edges of eachsquare wave output of the multivibrator 10. Only the egative pulseshould be eiiective to trigger the bistable circuit 20 and, unless themultivibrator circuit is made non-responsive to the positive pulsedeveloped across the resistor 16 by proper bias conditions, a rectifier107' is provided to remove the positive pulses from the input to thebistable circuit 20.

The output of the rectifier 107. is connected to the base electrode 102bof a PNP type transistor 102 forming part of the bistable circuit 20.This bistable circuit 20 has two stable states rather than one as in thecase of the monostable multivibrator circuit 10. The bistable circuit 20has another PNP type transistor 104. The base electrode 102b isconnected to one end of a resistor 106 whose opposite end is connectedto the gro-und line 53. The resistor 106 is connected to the negativeline 66' through series connected resistors 107 and 108. A capacitor 109is coupled in parallel with the resistor 107. A base electrode 104b ofthe transistor 104 is connected to one end of the resistor 110 whoseopposite end is connected to the ground line 53'. The resistor 110 isconnected to the negative line 66 through series-connected resistors 113and 115. The collector electrode 102g of the transistor 102 is connectedby a conductor 117 to the juncture between resistors 113 and 115. Thecollector electrode 10451 of the transistor 104 is connected by aconductor 118 to the juncture between resistors 107 and 108. The emitterelectrodes 102b and 104b of the transistors 102 and 104 are connectedthrough a common resistor 119 to the ground line 53. As is ycommon inbistable transistor circuits of this type, when one of the transistorsis highly conductive, the resulting bias conditions on the baseelectrode of the other transistor will render the latter transistornon-conductive. The conductive and non-conductive conditions of the twotransistors are reversed whenever a negative pulse is fed to the baseelectrode of a non-conductive transistor.

As previously indicated, the bistable circuit 20 is normally in a resetcondition effected by the feeding of a reference frequency pulse to theinput 44 of the bistable circuit 20. The bistable circuit is triggeredinto the opposite state by a negative beat indicating pulse fed to theinput 19 of the bistable control circuit.

The reference frequency pulses are derived from the alternating currentvoltage of a commercial power system. In FIG. 3, lines L1 and L2represent the two input conductors from the power system. An on-oiiswitch is connected between one of the power lines L1 and one end of theprimary winding 127a of a transformer 127. The other end of the primarywinding 127a is connected Yline 53.

to the power line L2. The transformer 127 has two secondary widings 127band 127e. One end of the secondary Winding 127b is connected by line 129to the ground line 53'. The other end of the secondary winding 127b isconnected by a resistor 131 and a rectifier 133 to a neon tube 134connected to the ground line 53. The rectifier 133 is also coupled tothe ground line 53' through a capacitor 135 in series with a resistor137. The various elements just described including theY neon tube 134form the aforementioned pulse forming circuit 3G. The rectifier 133removes the negative going portions of the alternating current voltagefrom the power lines L1 and L2 present in the secondary winding 127b,and passes the positive going portions thereof tothe capacitor 135. Whenthe charge onY the capacitor 135 reaches the tiring potential of theneon tube 134, the neon tube 134 fires and the bottom end of thecapacitor 135 is effectively grounded, which effects discharge of thecapacitor through the resistor 137 producing a negative pulsethereacross.

The resistor 137 forms a common emitter circuitre-q sistor for the firststage 36a of the frequency divider circuit 36. The firststage'36a isa-transistor bistable circuit substantially identical to the bistablecircuit 20, and thus a description of its operation will not be given.Suice it to say, each time a. negative pulse appears across the commonemitter resistor 137, the bistablefcircuit will be switched to adifferent state. The output of the first stage of the frequency divideris taken at the output terminal 140 and will comprise a single cycle ofa square Vwave for each pair of negative pulses fed to the resistor 137.The square wave is fed to a diiferentiating network comprising acapacitor 144 in series with a resistor 145. The resulting sharpnegative and positive pulses appearing across the resistor 145 are fedto a rectifier 146 which blocks the positive pulses and feeds thenegative pulses to the com-V mon emitter resistor 148 of the secondstage 36h of the frequency divider. This stage comprises a transistorbistable circuit which is also substantially identical to the bistablecircuit previously described. Suice it to say, for each negative pulsefed to the resistor 148, the state of the bistable stage 36h will bereversed. There will thus appear at the output terminal 149 of thesecond stage 36h of the frequency divider a square wave which has aperiod twice as long as the period of the square wave output of thefirst stage 36a since it requires the two negative pulses derived fromtwo cycles of the outputpofthe first stage 36a to complete-a cyclethereof. TheV square wave output at the output terminal 149 of thesecond stage 36b is fed to the aforementioned differentiating networkcomprising the capacitor 40 and the resistor 42 which provide positiveand negative pulses across -the resistor 42 for each cycle of thesquareV wave fed thereto. These pulses may beY fed through a rectifier151 which blocks the positive pulsesto the input 44Y of thebis'table'circuitV 20.

As previously explained in connection with the description oftheYoperation of FIG. l and the waveforms shown in FIGS. 2(a) through 2(7),there will appear at the output terminal 22 of the bistable circuit 20asquare wave having a negative going portion having a duration dependingupon the relative phase of the beat indicating pulse'last fed to thebistable circuit and the next reference frequency pulse.' Depending uponthefcondition ofthe watchv movement, the voltage waveform at the outputterminal V22 will resemble the waveforms shown in FIGS. 2(d), 2(g)' or2(1) but of inverse polarity to that shown therein.`

The vsquare wave output of the bistable circuit 20 is fed to one end ofa resistor 152-wliose other end is connected tothe base electrode 156bof a PNP transistor 156 formY ing part of the electronic switch 24.V Aresistor 1753 isv c connected between the base electrode 156b and theground The collector electrode 156a of transistor 156 is connected tothe Vnegative line 66' by a conductor 160. The emitter electrode 156e ofthe transistor Yisconnected by a resistor 162 to a normally closed jack164 into which an auxiliary measuring device may be plugged which opensthe closed contacts 164e thereof. The jack 164 is connected to the meter28 which, in turn, is connected to the juncture between resistors 166and 16S whose unconnectedends are respectively connected to the negativeline 66' and the ground line 53.

The emitter electrode 156e of the transistor 1156 is also connected to abranch circuit including a switch 170 in series Awith -a capacitor 17:2connected-to the ground line 53'. Normally the switch 170 is closed sothat the capacitor is effectively connected in parallel with the metercircuit to stabilize or average out the current flow therethrough.Although the movement of the meter pointer 28 is heavily damped, in theabsence of 4the capacitor 1712 it is still able to respond to thevarying durations of .successive current pulsations fed thereto byregistering .a deflection proportional to the duration of eachpulsation. This assumes that the time constant of the meter movement issuch that the pointer will not reach the maximum deflection point'fo-r acurrent pulsation of maximum width. This ena-bles the meter to indicatethe non-'symmetrical oscilla-tion of the Vbalance staff .at its oppositeextremes of movement, for

such a situation will produce 'beat indicating pulses of 4differentphase.

In the reset stateV of the .bistable circuit 20, the transistor 104 willbe highly conductive and the bias conditions on the bas-e electrode 156bresulting therefrom will ca-use the transistor 1-56 to be in `larelatively nonconductive state. When the bistable circuit 20 istriggered into its opposite state, the resulting non-conduction of thetransistor-104 will result in a highly negative voltage on the baseelectrode 1561: which causes the transistor 156 to conduct heavily until.the bistable circui-t is reset in the manner explained.

j When the switch v is closed to connect the capacitor 172 into thecircuit, the meter circuit becomes electrically damped to a point whereit cannot indicate the difference of the durations of two successivecurrent pulsations fed thereto. In effect, the capacitor averages outthe current waveform.

.In the circuit diagram of PIG. 3, the D.C. source 28 described in FIG.l'is a part of the power supply 34 which will now be described. Thepower supply 34 utilizes -the aforementioned secondary winding-127e` ofthe transformer 127. One end of this'winding is connected to the groundline 129 and the other end thereof is connected through a resistor 173to a rectifier 175 which passes only the negative portion of the A.C.waveform fed thereto from the transformer 127. 'Ihe output side of therectifier 175 'is connected to a filter ci-rcuit 177 including aresistor 179 4extending to the power supply line 66 and a pair of filtercapacitors 181 and 1-83 which filterv out voltage fluctuations in theD.C.

output of the power supply;

flection olfv the meter pointer 28.

' To Summarize .the operation Yof the invention, Vwhen the switches 125and 170 are closed and a watch Zris held adjacent the microphone 4, anaccurate beat frequency of the watch movement will be indicated bycasubstantial-ly Vconstant (although slightly vibrating) de- A-n imperfectbeat frequency of ,the watch movement will be indicated .by aprogressively varying deflection -of the pointer 28 over the facecf themeter. Upon opening of the switch T170,V a non-symmetrical beat of the4watch movement can be indicated by the'variation of the maximum de-4vement .and easy to;use,.reliable and accurate means for pointer. l Y

The present invention has thusfprovided a very contest-ing the beatfrequency of a Vwatch' movement and to the watch movement.

It should be understood that numerous modifications may be made of thepreferred form of the invention above described without deviating fromthe broader aspects of the invention.

What I claim as new and desire to protect by Letters Patent of theUnited States is:

1. Watch testing .apparatus for compa-ring the beat frequency of a watchmovement with that of a reference frequency: said apparatus comprising:a microphone and an amplifie-r coupled thereto for detecting the beat ofia watch movement and providing amplified beat indieating controlsignals corresponding to the beats of Ithe watch movement under test,means providing a source of reference con-trol signals at a fixedpredetermined frequency, the ratio of the frequency of one of thereference control signals and the correct beat frequency of the watchmovement to the other of same being a whole number greater than one, anelectrical measuring device responsive to the amplitude of an electricalsignal coupled thereto, a source of electrical energy for said device,switch means for coupling and uncoupling said source from said device,and switch operating bistable control means having respective statestriggered respectively by said beat indicating and reference controlsignals, and, in one of said states, operating said switch means Itoinitiate the coupling of said source of electrical energy to saidmeasuring device, and, in the other of said states, operating saidswitch means to decouple said source of electrical energy from saidmeasuring device, a constant indication of said measuring deviceindicating a correct beat rate ofthe watch movement under test and .anctuating indication of said measuring device indicating an imperfectbeat rate of the Watch movement.

`2. Watch testing apparatus for comparing the beat lfrequency of a watchmovement with that of a reference frequency: said apparatus comprising:a microphone .and an amplifier coupled thereto for detecting the beat ofa Watch movement and providing amplified beat indicating control signalscorresponding to the beats of the Watch movement under test, meansproviding a source of reference control signals at a xed predeterminedfrequency, the ratio of the frequency of one of the reference controlsignals and the correct beat frequency of the watch movement to theother of same being a whole number, an electrical measuring deviceresponsive to the amplitude of an electrical signal coupled thereto, asource of electrical energy for said device, switch means for couplingand uncoupling said source from said device, means for averaging theelectrical energy pulsations .applied to said device, means forselectively connecting and disconnecting said averaging meansselectively to cause said device to respond to the average andinstantaneous magnitudes of the electrical energy pulsations fedthereto, and switch operating means responsive to the beat indicatingand reference control signals for operating said switch means toinitiate the coupling .of said source of electrical energy fto saidmeasuring device `each time one of the control signals occur, andoperating said switch means to decouple said source of electrical energyfrom said measuring device each time the other control signal occurs, aconstant indication of said measuring device indicating a correct beatrate of said watch movement and a fluctuating indication of saidmeasuring device indicating an imperfect beat rate of said watchmovement.

3. Watch testing apparatus for comparing the beat frequency of a watchmovement with that of a reference frequency: said apparatus comprising:a microphone and an amplifier coupled thereto for detecting the beat ofa watch movement and providing amplified beat indicating control signalscorresponding to the beats of the Watch movement under test, said beatindicating signals comprising a series of spaced signal units eachcomprising e series of contiguous pulsations representing the vibrationsof one beat of the 4watch movement, means responsive to the first of thepulsations in each of said signal units for generating a square pulse ofgreater duration than the longest expected signal unit, differentiatingmeans for differentiating said square pulse and providing a singlenarrow beat indicating control pulse coinciding with the leading edge ofeach square pulse, means providing a source of reference control pulsesat a fixed predetermined pulse repetition rate, the ratio of thefrequency of one of the reference control pulses and the desired beatfrequency of the watch movement to the other of same being a wholenumber, an electrical measuring device responsive to the amplitude ofthe electrical signal coupled thereto, a source of electrical energy forsaid device, switch means for coupling and uncoupling said source ofelectrical energy to and from said measuring device, and switchoperating means for operating said switch means to couple said `sourceof electrical energy to said measuring device each time one of said beatindicating and reference control pulses occur, and for operating saidswitch means to decouple said source of electrical signals from saidmeasuring device each time the other control pulses occur, a constantindication of said measuring 'device indicating a correct beat rate ofsaid watch movement and a fluctuating indication of said measuringdevice indicating an imperfect beat rate of said Watch movement.

4. Watch testing apparatus for comparing the beat frequency of a watchmovement to that of a reference frequency: said apparatus comprising amicrophone and an amplifier coupled thereto for detecting the beat of awatch movement and providing amplified electrical signals correspondingto the beats of the Watch movement under test, the electrical signalscomprising a series of spaced signal units each comprising a series ofcontiguous pulsations representing the vibrations of one beat of theVwatch movement, monostable multivibrator means responsive to the firstof the pulsations in each of said signal units for providing a singlenarrow beat indicating control pulse coinciding with the start of eachsignal unit and having a vgreater duration than the longest eX- pectedsignal unit, means providing a source of reference control pulses at afixed predetermined pulse repetition rate, the ratio of the higher ofthe frequency of the reference control pulses and the desired beat rateof the watch movement to the other of same being a whole number, a DC.meter movement having a pointer indicating rate of said watch movement.

the current iow through the meter movement, a source of D.C. energizingcurrent for said meter movement, electronic switch means for couplingand uncoupling said source of D.C. current from said meter movement, andswitch operating bistable control means responsive to said controlpulses for operating said switch means to initiate the coupling of saidsource of D.C. current to said meter movement each time one of said beatindicating and reference control pulses occur, and operating said switchmeans to decouple said source of current from said meter movement eachtime the other control pulses occur, a consistent ydeflection of saidpointer indicating a correct beat rate of said Watch movement and aliuctuating deflection of said pointer indicating an imperfect beatReferences Cited bythe Examiner UNITED'STATES PATENTS 2,541,286 2/51Renaud 73--6 2,774,872 12/ 56 Howson 331-27 2,784,586 3/57 Campbell etal. 73-6 2,903,881 9/,59 Frolow 73-6 2,931,217 4/60 Wendt et al. 73-6ISAAC LISANN, Primary Examiner.

3. WATCH TESTING APPARATUS FOR COMPARING THE BEAT FREQUENCY OF A WATCH MOVEMENT WITH THAT OF A REFERENCE FREQUENCY: SAID APPARATUS COMPRISING: A MICROPHONE AND AN AMPLIFIER COUPLED THERETO FOR DETECTING THE BEAT OF A WATCH MOVEMENT AND PROVIDING AMPLIFIED BEAT INDICATING CONTROL SIGNALS CORRESPONDING TO THE BEATS OF THE WATCH MOVEMENT UNDER TEST, SAID BEAT INDICATING SIGNALS COMPRISING A SERIES OF SPACED SIGNAL UNITS EACH COMPRISING A SERIES OF CONTIGUOUS PULSATIONS REPRESENTING THE VIBRATIONS OF ONE BEAT OF THE WATCH MOVEMENT, MEANS RESPONSIVE TO THE FIRST OF THE PULSATIONS IN EACH OF SAID SIGNAL UNITS FOR GENERATING A SQUARE PULSE OF GREATER DURATION THAN THE LONGEST EXPECTED SIGNAL UNIT, DIFFERENTIATING MEANS FOR DIFFERENTIATING SAID SQUARE PULSE AND PROVIDING A SINGLE NARROW BEAT INDICATING CONTROL PULSE COINCIDING WITH THE LEADING EDGE OF EACH SQUARE PULSE, MEANS PROVIDING A SOURCE OF REFERENCE CONTROL PULSES AT A FIXED PREDETERMINED PULSE REPETITION RATE, THE RATIO OF THE FREQUENCY OF ONE OF THE REFERENCE CONTROL PULSES AND THE DESIRED BEAT FREQUENCY OF THE WATCH MOVEMENT TO THE OTHER OF SAME BEING A WHOLE NUMBER, AN ELECTRICAL MEASURING DEVICE RESPONSIVE TO THE AMPLITUDE OF THE ELECTRICAL SIGNAL COUPLED THERETO, A SOURCE OF ELECTRICAL ENERGY FOR SAID DEVICE, SWITCH MEANS FOR COUPLING AND UNCOUPLING SAID SOURCE OF ELECTRICAL ENERGY TO AND FROM SAID MEASURING DEVICE, AND SWITCH OPERATING MEANS FOR OPERATING SAID SWITCH MEANS TO COUPLE SAID SOURCE OF ELECTRICAL ENERGY TO SAID MEASURING DEVICE EACH TIME ONE OF SAID BEAT INDICATING AND REFERENCE CONTROL PULSES OCCUR, AND FOR OPERATING SAID SWITCH MEANS TO DECOUPLE SAID SOURCE OF ELECTRICAL SIGNALS FROM SAID MEASURING DEVICE EACH TIME THE OTHER CONTROL PULSES OCCUR, A CONSTANT INDICATION OF SAID MEASURING DEVICE INDICATING A CORRECT BEAT RATE OF SAID WATCH MOVEMENT AND A FLUCTUATING INDICATION OF SAID MEASURING DEVICE INDICATING AN IMPERFECT BEAT RATE OF SAID WATCH MOVEMENT. 